1. Field of the Invention
The present invention provides a thermoplastic resin composition excellent in chemical resistance and impact resistance and used as resin parts for home appliances, vehicles, etc., which are in an environment exposed to chemicals such as detergents and machine oil.
2. Description of the Related Art
Rubber reinforced styrene resins represented by ABS resin have been used as parts for home appliances, vehicles, etc., in a wide range of fields due to its excellent impact strength. As a result, the parts may sometimes be exposed to chemicals. For example, resin products such as wash stands and tap handles and shower heads in bath rooms are exposed to detergents; resin parts used in automobiles can be in contact with machine oil and wax removers; and resins used as handles and door caps of refrigerators can be exposed to flon chlorofluorocarbons which are foaming agents for urethane during the production of heat insulating materials for refrigerators. The resin products are often cracked, or fine cracks form on the surface thereof, under such circumstances.
The phenomenon, termed environmental stress cracking, appears when residual strain in the interior of molded rubber reinforced styrene resin products is partially released by contacting chemicals therewith, and is often observed when the resin products are contacted with chemicals having a low solubility in the resin.
There is a method for improving the chemical resistance (tendency towards environmental stress cracking) of the rubber reinforced styrene resin wherein crosslinked alkyl acrylate rubber is used as the rubber component. An example of the rubber reinforced styrene resin is AAS resin obtained by graft copolymerizing acrylonitrile and styrene with crosslinked butyl acrylate rubber. However, since AAS resin has a disadvantage that it has a low degree of impact strength, its use in resin products is markedly restricted. Though there may also be adopted means in which the rubber content is increased for obtaining a high degree of impact strength manifestation, the resultant resin products have lowered surface hardness and rigidity, and are easily scratched and deformed. Accordingly, the means is not preferable. The realization of rubber reinforced styrene resin excellent in both chemical resistance and impact strength manifestation has, therefore, been desired.